Recording head for a jet array recorder

ABSTRACT

There is disclosed a recording head for a jet array recorder wherein the electrical components thereof are attached to a supporting yoke and the fluidic components thereof are suspended within the yoke. The primary fluidic components are separately assembled as a manifold subassembly and suspended inside a wobble plate. The wobble plate in turn is inserted inside an inner yoke, and rides within an O-ring which provides freedom of movement for vertical adjustment and tilting. Thus the manifold subassembly, which includes an orifice plate provided with one or more rows of jet orifices, may be accurately positioned with respect to the inner yoke. In final assembly the inner yoke is mounted inside the main supporting yoke to which the electrical components have been attached and aligned. A set of dowel pins is provided to insure alignment between the inner yoke and the outer yoke. There is also disclosed means for supplying a flow of purging air through the recording head and a magnetic catcher mounting arrangement. The purging air is supplied to an air tube fitting which attaches to the manifold subassembly. In the completed assembly the air flows around the outside of the orifice plate and then exits the recording head by flowing outwardly through apertures in a charge ring plate which is fastened to the lower surface of the main yoke. The catchers are mounted below the charge ring plate by attraction to a set of permanent magnets which are set into the lower surface of the main yoke.

United States Patent 1191 Burnett et al.

[451 Sept. 17, 1974 RECORDING HEAD FOR A JET ARRAY RECORDER [73]Assignee: The Mead Corporation, Dayton,

Ohio

22 Filed: Dec. 20, 1972 21 App]. No.: 317,075

[52] US. Cl. 346/75 [51] Int. Cl. G0ld 15/18 [58] Field of Search 346/75[56] References Cited UNITED STATES PATENTS 2,577,894 12/1951 Jacob346/75 3,701,998 10/1972 Matais 346/75 Primary Examiner-Joseph W.Hartary Attorney, Agent, or Firm-Biebel, French & Bugg [57] ABSTRACTThere is disclosed a recording head for a jet array recorder wherein theelectrical components thereof are attached to a supporting yoke and thefiuidic components thereof are suspended within the yoke. The primaryfluidic components are separately assembled as a manifold subassemblyand suspended inside a wobble plate. The wobble plate in turn isinserted inside an inner yoke, and rides within an O-ring which providesfreedom of movement for vertical adjustment and tilting. Thus themanifold subassembly, which includes an orifice plate provided with oneor more rows of jet orifices, may be accurately positioned with respectto the inner yoke. In final assembly the inner yoke is mounted insidethe main supporting yoke to which the electrical components have beenattached and aligned. A set of dowel pins is provided to insurealignment between the inner yoke and the outer yoke.

There is also disclosed means for supplying a flow of purging airthrough the recording head and a magnetic catcher mounting arrangement.The purging air is supplied to an air tube fitting which attaches to themanifold subassembly. In the completed assembly the air flows around theoutside of the orifice plate and then exits the recording head byflowing outwardly through apertures in a charge ring plate which isfastened to the lower surface of the main yoke. The catchers are mountedbelow the charge ring plate by attraction to a set of permanent magnetswhich are set into the lower surface of the main yoke.

8 Claims, 5 Drawing Figures RECORDING HEAD FOR A JET ARRAY RECORDERCROSS REFERENCE TO RELATED APPLICATIONS This application is related toapplication Ser. No. 317,076 and Ser. No. 3 I 7,073 which were filed oneven date herewith and assigned to the assignee hereof.

BACKGROUND OF THE INVENTION This invention relates to a recording headfor jet drop recording apparatus, and more particularly to a recordinghead which generates one or more rows ofjet drop streams. Typical priorart recording heads are disclosed, for example, in Beam et al US Pat.No. 3,586,907 and Mathis US Pat. No. 3,701,998., In such prior artarrangements the jet streams are created by forcing a printing fluidunder pressure through one or more rows of orifices in an orifice plateand stimulating the plate to cause break up of the streams intouniformly sized drops. Further in these prior art recording heads theorifice plate is bonded to a manifold into which the recording fluid isintroduced, and other necessary recording head elements are attached tothe manifold directly below the orifice plate. Thus the recording headcomprises an ink manifold, an orifice plate, a charge ring plate, one ormore deflection strips, and one or more catchers, all assembled in astacked arrangement.

It has been found that such prior art arrangements are inconvenient forassembly and cleaning, and that in normal operation there is a tendencyfor dust and dirt to enter the assembly from the outside.

SUMMARY OF THE INVENTION This invention provides improved means forassembling and handling a recording head for jet array recorder. Inparticular there is provided a yoke into which the fluid holdingmanifold is suspended. The orifice plate is attached to the manifold asin the prior art, but other elements of the recording head are attachedto the yoke. Thus there is a physical segregation between the electricaland the fluidic elements of the head. Consequently each of these groupsof elements may be assembled and checked out independently and broughttogether in final assembly, This means that if an operating difficultyis experienced because of orifice clogging or the like, the manifoldsubassembly, which includes the orifice plate, may be removed from theyoke without disturbing the charge plate, deflection ribbon(s), orcatcher(s). The yoke may have alignment means thereon so that in thecaseof the above example, a replacement manifold subassembly may besuspended in the yoke with the original electrical elements still inplace. I

In a preferred embodiment of-the invention there may be employed aninner yoke as well as a main yoke and a wobble plate which fits withinthe inner yoke. The manifold subassembly is fastened to the wobble platewhich is configured for adjusting movement within the inner yoke. Thereis thus provided considerable freedom ofmovement for aligning theorifice plate and directing the jets along correct trajectories relativeto the charge ring plate. Further, there may be vprovided an air passageimmediately above the charge ring plate and around the manifoldsubassembly. A connection may be made to this space from the outside forsetting up a continuous flow of purging air, and thereby preventingingestion of any dirt or dust into the printer head.

Accordingly it is an object of this invention to provide improved meansfor assembling a recording head for a jet array recorder. It is anotherobject of this invention to provide means for air purging of a printerhead for a jet array recorder.

Other objects and advantages of the invention will be apparent from thefollowing description, the accompanying drawings and theappended'claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded pictorial viewof a jet array printer head employing the invention in a preferredembodiment;

FIG. 2 is an upwardly looking view of a fully assembled printer head;

FIG. 3 is a view taken along lines 3--3 of FIG. 2;

FIG. 4 is a view taken along lines 44 of FIG. 2; and

FIG. 5 is a view taken along lines 55 of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of theinvention is illustrated in exploded form in FIG. I as including amanifold subassembly 10 which fits into a wobble plate 15. Wobble plate15 fits into an inner yoke 16 which in turn fits within a main yoke 17.There are also provided a charge ring plate 32, a deflection ribbon 33,and a pair of catchers 18, all of which are fastened to the lowersurface of main yoke 17 as hereinafter described.

Manifold subassembly 10 comprises a manifold bar 11, a cover plate 29,an orifice plate holder 12, and an orifice plate l3 which fit togetheras illustrated in FIGS. 1 and 4. Thus orifice plate holder 12 fitsupwardly into a cavity in the lower surface of manifold bar 11. Orificeplate holder 12 may be secured in place by screws (not shown) and afluid tight seal is provided between orifice plate holder 12 andmanifold bar 11 by an O-ring l4. Orifice plate I3 is preferably solderedin place against the lower surface of orifice plate holder 12. Manifoldsubassembly 10 is thus an integral unit which may be assembled andflushed clean prior to any asso-' ciation with any of the electricalcomponents of the recording head,

As further illustrated in FIG. 1, manifold bar 11 and cover plate 29 areprovided with internal passages into which may be inserted an ink supplytube 20, an ink return tube 21, a stimulator 23, and an air tube fitting24. Stimulator 23 has a probe which reaches-downwardly for contact withorifice plate 13. Orifice plate 13 is excited to propagate a series oftraveling bending waves as described in detail in Lyon et al., Ser. No.189,297, and stimulator 23 is rotatably adjustable as described inHouser, US. Pat. No. 3,701,476. Air tube fitting 24 is used for applyinga flow of purging air to the recording head. A flow of air suppliedby afan or othermeans (not shown) flows downwardly through air tube fitting24 and thence into an air cavity 25 in manifold bar 11. The purging airthen follows a path as generally illustrated in FIG. 4 to exit therecording head through charge ring apertures 26 in charge ring plate 32.This keeps foreign matter out of the charge ring apertures and alsoprovides a stabilizing effect for the liquid jets. The jet stabilizingeffect, which forms no part of this invention, is described in Sweet,US. Pat. No. 3,596,275.

Once assembled, manifold subassembly is fitted downwardly into wobbleplate and fastened thereto as by screws (not shown). Wobble plate 15,with manifold subassembly 10 attached thereto, is fitted downwardly intoinner yoke 16 with an O-ring 27 therebetween. It will be appreciatedthat wobble plate 15 may be adjusted upwardly or downwardly or tiltedwithin inner yoke 16 for adjustment of jet filament lengths to meetrequirements as discussed in Ser. No. 189,297. For this purpose thereare provided three lifting screws 65 and three hold down screws 66.

Independently of the assembly of manifold subassembly 10, the electricalelements of the recording head may be assembled as a unit by fasteningto main yoke 17 as illustrated also in FIG. 1. Charge ring plate 32 isattached directly to the main yoke 17, as are also catchers 18. Chargering plate 32 is fastened in place by a series of screws, and catchers18 are secured by means of four cylindrical magnets 34 which are bondedinto recesses in the lower surface of main yoke 17. Magnets 34 arecommon insulated ceramic magnets which are commercially available frommany sources. Preferably magnets 34 are made of barium-ferrite ceramicembeddedin insulating plastic and are provided with lead-out polepieces. Catchers 18 are preferably fabricated from a magnetic stainlesssteel material so that they are firmly grasped by magnets 34.

Lateral adjustment of catchers 18 is provided as best illustrated inFIG. 5 by set screws 35 and adjusting nuts 36. Each adjusting nut 36 isprovided with a small downwardly projecting pin 37 which reaches into amating slot in the upper surface of the associated catcher 18. Setscrews 35 reach through openings in yoke 17 for threaded engagement withnuts 36. Thus catchers 18 may be adjusted inwardly or outwardly toprovide any desired spacing between the catcher faces and the surfacesof deflection ribbon 33. Catchers 18 are elongated devices as describedin detail in copending patent application, Docket 5725. Each catcher isequipped with two vacuum tubes 41 and one vacuum tube 59.

Deflection ribbon 33 is stretched between a pair of tension blocks 38which in turn are fastened to main yoke 17 as by screws 39. Tensionblocks 38 are provided with set screws 40 so that the tension blocks maybe adjusted back and forth in the longitudinal direction (see P16. 2).Set screws 40 are initially adjusted to enable easy insertion ofdeflection ribbon 33 between tension blocks 38. Thereafter deflectionribbon 33 is drawn to a taut condition. I

In operation there are created two rows of drop streams which areselectively charged and caught all as described in detail in Mathis, US.Pat. No. 3,70l ,998. For this purpose charging signals representative ofgraphic information are applied to terminals 42 of charge ring plate 32.These charging signals cause selective charging of drops 44 (see FIG. 4)which are directed toward a recording medium 43. A static electricalfield for the deflection of the charged drops is set up between thedeflection ribbon 33 and each of catchers 18. Appropriate deflectionfields are set up by attaching deflection ribbon 33 and catchers 18 tosources of different electrical potential. Preferably catchers 18 aregrounded, and deflection ribbon 33 is connected to a source of highnegative potential. Accordingly the data system (not shown) applies apositive electrical pulse to one of terminals 42 for each drop or droppacket which is to be caught. These drops, which are negatively chargedin response to such pulses, are deflected to impact against the face ofone of catchers 18 for ingestion therein. Those drops which are notcharged strike recording medium 43 to produce a graphic impression.

it will be appreciated that the alignment tolerances between orificeplate 13 and charge ring plate 32 are quite critical. Accordingly themounting apertures in charge ring plate 32 and cover plate 29 areoversize to permit minor alignment correcting adjustments. In the usualassembly process manifold subassembly 10 is mounted within wobble plate15, and thereafter the combined assembly is mounted within inner yoke16. At this point wobble plate 15 may be adjusted and cover plate 29 maybe shifted for precise positioning of orifices 29 relative to inner yoke16. Then charge ring plate 32 may be mounted on main yoke 17 with chargerings 26 accurately positioned after which inner yoke 16 is fitted intomain yoke 17. A pair of precisely positioned dowel pins 45 insureaccurate alignment of yoke 16 with yoke 17 and hence accuratepositioning of orifices 28 relative to charge rings 26. Alternativelythe head may be assembled as above described, but with orifices 28 beingdirectly aligned relative to charge rings 26 as a post assemblyprocedure. This latter adjustment procedure may be carried out on atrial run basis with a suitable liquid actually filling the recordingfluid manifold and forming into jet drop streams. In any event, once therequired alignment has been achieved, inner yoke 16 may be removed frommain yoke 17 as desired for cleaning or flushing of the fluidcomponents. Then so long as the adjusting screws have not been touched,the head may be reassembled without further aligning adjustment. Thusthere is achieved a practical segregation between the fluidic and theelectrical components of the recording head.

While the form of apparatus herein described constitutes a preferredembodiment of the invention, it is to be understood that the inventionis not limited to this precise form of apparatus, and that changes maybe made therein without departing from the scope of the invention.

What is claimed is:

l. A recording head for a jet drop recording apparatus comprising:

a main yoke,

a second yoke mounted within said main yoke,

a manifold subassembly mounted within said second yoke, said manifoldsubassembly comprising a manifold bar having a cavity therein and anorifice plate provided with a plurality of orifices comm unicating withsaid cavity, and

a charge ring plate provided with a plurality of charge rings andmounted on said main yoke with said charge rings in alignment with saidorifices.

2. Apparatus according to claim 1 further comprising a wobble plate forreceiving said manifold subassembly and adjustably mounting saidmanifold subassembly within said second yoke.

3. Apparatus according to claim 1 said manifold subassembly furthercomprising an orifice plate holder mounted within said cavity in saidmanifold bar for supporting said orifice plate.

4. Apparatus according to claim 1 further comprising means forcirculating a flow of purging air into said main yoke for exit therefromthrough said charge rings.

5. Apparatus according to claim 4 said manifold bar being provided withan air passage to receive said flow of purging air, and said manifoldsubassembly being supported by said second yoke for creation of a secondair passage connecting with the first said passage and leading to aspace between said orifice plate and said charge ring plate.

6. A jet drop recording head comprising:

a main yoke,

a charge plate mounted on said main yoke,

a pair of catchers mounted symmetrically on said main yoke in spacedrelation to said charge plate,

a deflection ribbon mounted on said main yoke between said catchers,

an inner yoke mounted within said main yoke,

a wobble plate mounted within said inner yoke,

a manifold bar mounted within said wobble plate,

an orifice plate holder mounted within said manifold bar, and

an orifice plate bonded to said orifice plate holder in alignment withsaid charge plate.

7. Apparatus according to claim 6 further comprising at least two dowelpins for aligning said inner yoke within said outer yoke.

8. Apparatus according to claim 6 said orifice plate being mounted inspaced relation to said charge plate and said apparatus being providedwith an internal air passage connecting with the space between saidplates and leading to an air inlet port.

1. A recording head for a jet drop recording apparatus comprising: amain yoke, a second yoke mounted within said main yoke, a manifoldsubassembly mounted within said second yoke, said manifold subassemblycomprising a manifold bar having a cavity therein and an orifice plateprovided with a plurality of orifices communicating with said cavity,and a charge ring plate provided with a plurality of charge rings andmounted on said main yoke with said charge rings in alignment with saidorifices.
 2. Apparatus according to claim 1 further comprising a wobbleplate for receiving said manifold subassembly and adjustably mountingsaid manifold subassembly within said second yoke.
 3. Apparatusaccording to claim 1 said manifold subassembly further comprising anorifice plate holder mounted within said cavity in said manifold bar forsupporting said orifice plate.
 4. Apparatus according to claim 1 furthercomprising means for circulating a flow of purging air into said mainyoke for exit therefrom through said charge rings.
 5. Apparatusaccording to claim 4 said manifold bar being provided with an airpassage to receive said flow of purging air, and said manifoldsubassembly being supported by said second yoke for creation of a secondair passage connecting with the first said passage and leading to aspace between said orifice plate and said charge ring plate.
 6. A jetdrop recording head comprising: a main yoke, a charge plate mounted onsaid main yoke, a pair of catchers mounted symmetrically on said mainyoke in spaced relation to said charge plate, a deflection ribbonmounted on said main yoke between said catchers, an inner yoke mountedwithin said main yoke, a wobble plate mounted within said inner yoke, amanifold bar mounted within said wobble plate, an orifice plate holdermounted within said manifold bar, and an orifice plate bonded to saidorifice plate holder in alignment with said charge plate.
 7. Apparatusaccording to claim 6 further comprising at least two dowel pins foraligning said inner yoke within said outer yoke.
 8. Apparatus accordingto claim 6 said orifice plate being mounted in spaced relation to saidcharge plate and said apparatus being provided with an internal airpassage connecting with the space between said plates and leading to anair inlet port.